1. Field of the Invention
The present invention generally relates to test sample fabrication techniques and more specifically, to a infrared detector material test sample fabrication technique.
2. Description of Prior Art
A potential advancement for high performance in these uncooled systems is the development of a thin-film pyroelectric detector material for use in uncooled infrared focal plane array (IRFPA) systems. Characterization of these thin film detector materials requires the development of techniques different from those used to-date for bulk pyroelectric and ferroelectric infrared detector materials. With the bulk materials, quasi-static characterization has been used most often, particularly in the early screening stages, to select promising materials for further study. For application in IRFPAs, these quasi-static measurements have limited usefulness, since they are not accurate predictors of device performance at dynamic (60 Hz) frame rates.
In cases where numerous samples of a single material are to be characterized, a method called the Chynoweth method, using chopped IR radiation, has been used with reasonable success to provide dynamic figure of merit estimations. This method requires knowledge of the thermal conductivity, heat capacity, and infrared absorptivity of the test sample. For a thin-film test sample with a thermal-isolation layer, knowledge of the thermal conductivity and thickness of each layer would be required. Because thin-film thermal and optical properties vary widely, depending on the exact deposition process parameters, it cannot be assumed that these properties remain the same from sample to sample. It is also time consuming to determine these properties for each material to be tested. A test procedure based on a sample structure that requires minimal knowledge of thin-film material properties would be more useful.
While the prior art has reported the use of various test samples it has not established a basis for a specific test sample that is dedicated to the task of resolving the particular problem at hand. What is needed in this instance is a fabrication technique of a test sample designed expressly for the measurement of thin-film temperature responsivity.